You've discovered the general principle yourself -- while clobbers $_, while for implicitly localizes it. The most common suggestion is to use a lexical loop variable in your for loop:

for my $b (@bb) {
    while (<STDIN>) {
        print "while=$_\n";
        last;
    } 
    print "forwhile=$b\n";
}

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In reply to Re: While but not for clobbers $_ by chromatic
in thread While but not for clobbers $_ by tenya

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